Csing couplings are manufactured as per API Spec 5CT, using seamless process. Csing couplings are manufactured as per API Spec 5CT, using seamless process(steel tube or forged), available material grade include: H40, J55,M65,N80, L80, C90, T95, P110,Q125, thread types include: STC, LC, BC, XC. Casing coupling